Process of making clad metals.



w; M. PAGE. PROCESS OF MAKING GLAD METALS.

APPLICATION FILED JUNE 28, 1910. RENEWED JUNE 10, 1913.

1 ,084,47%. Patented J an. 13, 1914.

81 we mfo'a q qh-lmeooca claimed.

' the processes of Patent #853,? 16 and by the point,

WILLIAM MARSHALL PAGE,

OF PHILADELPHIA, PENNSYLVANIA.

PROCESS OF MAKING GLAD METALS.

Specification of Letters Patent.

Application filed June 28, 1910, Serial No. 569,302. Renewed June 10, 1913. Serial No. 772,879.

To all whom it may concern:

Be it known that 1, WILLIAM MARSHALL PAGE, a citizen of the United States,'residing at Philadelphia, in the county of Philade phia and State of Pennsylvania,have invented certain new' and useful Improvements'in Processes of Making Clad Metals, of which the following is a specification.

This invention relates to processes of making clad metals; and it comprises a method of making clad metals, and particularly copper clad steel, wherein a billet of metaL is first film-coated to secure a weld united coating and is thereafter coated with a substantial body of metal by casting a body of coating metal through a restricted orifice into contact with such'filmed surface; all as more fully hereinafter set forth and as It is not easy to obtain a good, substantial and permanent union between steel and copper but such a union is now practicable by methods of my copending application Serial No. 467,651. If a clean steel surface be brought into contact with copper heated several hundred degrees above its melting a union can be elfected, which on cooling will Withstand violent temperature changes and torsion to rupture, and which cannot be discovered b cleaving tools such as a cold chisel. Or if the steel surface be decarbonized so as to. give a substantially carbon-free surface layer of iron, the union be efiected by casting copper thereagainst 'ata lower temperature. This decarbonization may be effected by forming a coating of magnetic oxid on a steel billet, as by exposure'to superheated streaming steam and thereafter causing the magnetic oxid and the carbon of the underlying metal to react with each other to form pure iron, such iron coming both from the oxid and from the underlying meta This reaction may be performed by simply submerging the oxidized billet in molten copper. In the ordinary practice of making copper clad steel, it is customary to film coat the billet by dippin it into molten copper under the proper con itions to secure a weld union and thereafter unite with. the filmed surface a substantial body of the coating metal. This double coating operation is performed for several reasons. For one thing, it is a relatively expensive operation to maintain a large body of coating metal in a. highly.

heated and carefully controlled state, and it is simpler and easier merely for film coating, putting on the mam body of copper from another source. Furthermore, the copper which is used for dipping or film coatin the billet is more or less contaminated by dissolved iron; and while for the purpose of producing the preliminary or film coating the presence of this iron is desirable since it causes a readier union yet for electrical purposes it is highly desirable-that the main body of the coating shall contain no iron or substantially none, the presence of a fraction of a per cent. of iron in copper running down .its conductivity inordinately. The double operation is therefore also desirable as permitting the main body of the coating to purified metal.

In attaching the second and substantial coating of copper to the film coated billet many precautions are necessary. The molten copper must not be brought into contact therewith in such a way as to wash-off the film coating, sincethis would result in the diffusion of iron through the body of the copper. For the same reason of preventing contamination it is desirable not to use the molten copper for the substantial coating in a highly heated state. The film coating being largely alloyed with iron is relatively fusible and is readily melted off.

In the ordinary practice of the double coating operation, the cleaned or oxidized steelbillet is placed in an open bottomed casing. This casing during the operation is maintained full of producer gas to ob viate oxidation of the steel or of the copper coating. Billet and casing are hoisted together above a bath of copper of the proper composition and temperature, the billet thrust beneath the surface of the molten copper and there maintained for a period of time sufficient to produce an alloying and union of the two metals. The billet is now withdrawn from the copper into the easing, and as withdrawn it is found to be covered with a thin clinging film of copper and copper iron alloy. The bottom of the casing containing the filmed billet is next closed. This may be done by screwing a cap on the end of the filmed billet, the cap being one which is adapted to make a fluidtight contact with the bottom of the casing, The casing is provided with orifices near its top covered by a temporary seal of asbestos Patented Jan. 113 1914.

be made of specially to use this body cloth or the like Casing, billet and cap are next lowered into another bath of copper of the desired purity, the casing being lowered until the copper covers and flows in through the orifices, the asbestos being removed. These orifices being of restricted size it is possible to keep them covered by a body of molten copper so that air cannot enter. The temperature of the copper and of the casing are preferably so correlated that the copper flowing in through the orifices shall solidify first next the wall while later entering copper progressively fills up the space between the cop er already solidified and the filmed surface 0 the billet. The portion of copper which solidifies next the wall cannot become contaminated by iron from the film coating. The entering copper may run down and solidify next the wall and be solidified as successive inward layers. Or it may enter in such a manner as to form, so to speak, a constantly upwardly growing rim of solidified co per next the mold wall with later solidifying liquid copper between this rim and the film coating. The important thing is to prevent contamination'of the outer layers of copper, restricting all contamination by the film coating to the layers next thereto, this contamination being rendered as slight as may be.

The. dipping of the whole mold with an included billet in a bath of copper is an expensive and inconvenient operation. It requires a bath of copper of a size larger and depth greater than those of the casing, and practically only round casings can be used. But where it is desired totsecure a high purity of the coating, as is the case with all clad metal intended for electrical purposes, it has not heretofore proved practicable to pour or cast melted copper directly into the mold at its top-in the ordinary way of making castings. Direct casting does not give as good results for this purpose as this operation of submerging mold, billet and all beneath the surface of a large body of molten copper. In direct pouring it is difiicult to make the copper solidifynext the mold wall prior to contact of the molten copper with the film without contamination from the filmed surface. And in pouring in, the molten copper passes into and through a body of air which it carries along with it into the mold, tending to make a blowy casting and to become oxidized. The oxidation renders diflicult a good union between the cast-in copper and the copper of the film. If the cast-in copper be hot enough to give a good gravital se aration of oxid it will wash or dissolve o the filmcoating and become contaminated.

In the present invention I have devised a new way of bringing the copper for the substantial coating 1nto the mold which avoids the stated disadvantages of casting and obtrough.

tains the advantages of the dip-molding operation. In lieu of casting the copper directly into the space between the filmed billet and the mold body, I providethe mold body with one or more gutters or troughs near its top communicating with the interior of the mold in the side wall through relatively small orifices. This gutter may or may not entirely surround the mold, this depending on tie shape and size of said mold. The mold may be round or square or any other shape. annular gutter is convenient. Upon casting the copper into this gutter the conditions of the dip molding operation are simulated, a body of copper covering and entering the restricted orifices in the side walls. During the entire orifices are kept covered and sealed by molten copper. The entering copper is; caused to solidify first next the mold wall as described. During the operation the mold may be kept full of producer gas. Under these conditions, oxidation is obviously impossible. Whatever oxid is formed in casting through the air remains with the copper in the Enough copper should becast into the trough to keep the orifices covered while the main body of the coating is formed. By ceasing to pour at this time, this sealing copper (which will be contaminated by gas and floating oxid) runs in above the top of the billet whence it can be later removed. Or by providing the casing with minute orifices above the level of the end of the intended coating on the billet, this last copper can be again drainedout. By casting copper into the gutter and maintaining enough copper there to cover the orifices during the casting operation passed into the mold. As stated, at the completion of the casting, the excess of copper may be drained out tlirough these small orifices in the side of the mold, which may be provided with a suitable closure.

The coating operation is made much more flexible by the described process .since the size and shape of. the mold need not conform to the dimensions and shape of the vessel containing the molten copper as is necessary in dip-molding. The mold can be square or of any shape desired, and need not be the protective casing employed during the film be a separate O'ne filming casing may coating operation but may piece of apparatus. supply filmed billets coating molds. of submerging a strong and heavy mold in the molten copper at any stage of the operation cheaper casings and molds may be emfor a number of heavy ployed.

In the accompanylng illustration I have shown, more or less diagrammatically,

means and material for accomplishing the described process. In this showing the casting operation, these.

IO er no air can be '5 And since there is no need With a round mold an figure represents a vertical section of the apparatus.

Element 1 is a furnace chamber shown as lined with refractory material 2. This chamber as shown is of generally cylindrical shape and is intended to be fired by oil flames or the like, from end burners, (not shown). The furnace chamber is mounted for tilting upon rollers 3, and is provided with counterpoise means l. The furnace chamber is further provided with a port 5 which may be closed by swinging door 6. Through this port it may be replenished with metal and the port also serves as a waste gas removing means. It is also provided with a side duct 7 leading to an offset pocket 8. This pocket is provided with a dipping port 9, which may be merely large enough to admit a billet, or may admit also the.end of the filming casing, and with a pouring lip 10. Ram 11 allows the tilting of the furnace into any desired position.

. When swung 1nto one position the copper its base, the billet may carry 'tion.

will flow back into the flame chamber. while when swung into another the molten copper will, as shown, accumulate in the dipping pocket. This enables the copper to be purified, heated and treated in one chamber and then transferred to another for filming without danger of intermediate contamina- The mold or casing 12 is shown as adapted for both filmingand coating and as containing a billet 13, carried by porterbar 14:. This porterbar and the hoisting means 15 allow independent motion of casing and billet. Near the top of the casing are inlet orifices 16 which may be covered and sealed by a strip of asbestos or the like 17. Connecting with these orifices is a gutter or channel 18 which may or may not'be continuous around the mold, this depending on convenience. As shown, the mold or casing is round and provided with a continuous annular gutter. A neutral atmosphere may be maintained in the casing during the various operations by means of gas, such as producer gas, passed in through 19. At

a cap 20 adapted to seat and engage with ribs 21 of the casing to make a fluid-tight joint. The cap may be screwed to the billet by screw threaded means 22 (shown as exaggerated in size). In the molding operation proper, copper may be cast into the gutter either from the pouring lip of the coating furnace described, or from a separate crucible or ladle .23. The mold is provided with small venting or draining orifices 25 which may be kept closed by band 26.-

In the use of the described apparatus the coating furnace may be tilted into a position where the copper will flow back into or re- -main in the cylindrical chamber shown.

"Here it may be heated and brought to any temperature desired, and'may also be puridipping pocket.

. oxids and oxygen,

I the copper.

.ters of the mold. In practice,

fied. During this operation door 6 will be closed, and the through dippingport 9, which nowserves as a waste gas exit. This serves to heat the When the copper is brought to the proper temperature and composition the furnace is swung into the position shown in the drawing, when the copper will flow into the dipping pocket, the waste gases now escaping through 5, door 6 being swung out of the way for thispurpose. The casing is lowered to or into the dipping port and the billet 13, which has been previously treated in any way desired, is lowered into the molten copper; and maintained beneath its surface until the desired amount of alloying has taken place and it is provided with a weld-united film. It is now raised and brought back into the casing, cap 20 affixed, if not already attached, and

caused to make a tight joint with the bottom of the casing. The billet and casing are now placed upon floor 24:, the asbestos seal 17 removed and copper poured into the casting channel, this copper coming from pouring lip 10' or from ladle 23, and being of any special composition and temperature desired. Or, alternatively, in lieu of attaching the end cap to the billet and using the protective casing as a mold, the filmed billet may be removed from the first dip coating casing and lowered into another mold for the coating operation. For electrical goods, the coating copper is best taken from another furnace than the one which is serving for the dipping operation since, as stated, in the dipping the copper is contaminated more or less by iron. The contamination by iron of the copper in the furnace shown after the filming operation may however be obviated and certain advantages gained by then tilting the furnace back into the melting position and burning out the dissolved iron fromthe copper. \Vhen iron is dissolved in copper, as it is in the filming operation, it effectually removes dissolved may be efiectually removed by a subsequent preferential oxidation without re-oxidizing In this preferential oxidizing operation the surface of the molten copper should be covered and protected by floating carbon, such as charcoal or coke, and flame then impinged on the protected surface. Under these conditions, iron will burn out, leaving the copper pure and unoxidized. In the presence of the carbon, the surface of the steel is blanketed by carbon dioxid and carbon monoxid gases, both of which have an oxidizing effect on iron. but not on copper. The purified copper may now be employed forthe main coating by casting into the gutthe copper in a given furnace may be employed for dipping a number of billets, thereby becoming while the excessof iron.

flame gases will escape purified from oxygen and oxids and com taminated byiron, may then be treated to floating on the pool remove the dissolved iron and then be used for billets filmed in another similar furnace. But in the ordinary course of the work it is generall better. to use a separate supply of copper or the main body of coating. This may be melted and purified in crucible 23 which then may be used as a ladle. Two such furnaces as alternation, one being usedfor the-dipping operation until the copper is free of oxygen but full of dissolved iron, while the other is supplying purified, copper, and conversely. making electrical materials, the mold used for the coating operation is preferably kept during the coating operation at such a temperature that the infiowing copper will solidi next its walls in the manner describe In the casting operation, the copper accumulates in the gutter above the level of the restricted orifices, sealing them against entrance of air or entangled oxid. The oxid formed in pouring through the air, remains of copper while clean copper is tapped into the mold through the orifice below the copper surface. This sealing by molten co per is maintained throughout the time nee ed to introduce enough copper to fill the space between the mold walls and the filmed billet. After the copper rises above the endof the billet, entrance of air and oxid is unimportant. In other words, the copper is cast into the gutter at a-somewhat greater rate than it can pass therefrom into the mold through the restricted orifices. At the endof the pouring, the molten copper in the gutter passes into the mold where it may remain to solidify and later be cut ofl"; or it may be again drained away through drain holes 25, sealing band 26 be ing removed. During the casting operation, the head of molten copper in the gutter should not be high enough to cause'any very forcible projectioninward. into the mold or any Spurting inward flow.

What I claim is I 1. The process of making clad metals which comprises placing a billet of core metal within a suitable mold casing and casting molten coating metal into a channel communicating with the interior of said mold through arestricted orifice in its side until a coating is formed, the size of the orifice and the speed of pouring being so correlated that liquid coating metal remains in said channel above the level of and seals said orifice until the coating is formed. v

2. The process of 'making clad metals which comprises placing a billet of core metal within a suitable mold casing, and casting molten coating metal into a channel communicating with the interior of said mold through a restricted orifice until a those shown may be used in .level of said orifice until the I coating is formed, the size of the orifice and the speed of pouring being so correlated that liquid coating metal remains in said channel above the level of said orifice until the coating is formed, andthe temperature of said mold and of said molten metal being socorrelated that entering metal first solidifies next the inner wall of the mold while later solidifying metal fills up the space between said first solidified metal and said billet.

3. The process of making clad metals which comprises placing a billet of steel Within a suitable mold casing and casting molten copper into a channel communicating with the interior of said mold through a restricted orifice in its side until a coating is formed, the size of the orifice and the speed of pouring being so correlated that liquid copper remains in said channel above the level of said orifice until the coatiiig is formed.

4. The

process of making clad metals which comprises placing a billet of steel within a suitable mold casing and casting molten copper into a channel communicating with the interior of said mold through a restricted orifice until a coating is formed, the size of the orifice andthe speed of pouring being so correlated that liquid copper remains in said channel above the level of said orifice until the coating is formed, and the temperature of said mold and of said molten metal being so correlated that entering metal first solidifies next the inner wall while-later solidifying metal fills up the space between said first solidified metal and said billet.

5. The process of making copper clad steel which comprises film-coating a steel billgt withtcopper, maintaining the filmed bille within a suitable mold casing and casting molten copper into a channel communicating with the interior of said mold through a restricted orifice until a coating is formed, the size of the orifice and the speed oi pouring being-so correlated that liquidcopper. remains in said channel above the coating is formed.

6. The process of making copper clad eel which comprises film-coating a steel billet with copper, maintaining the filmed billet within casting molten copper into a channel communicating with the interior'of said mold through a restricted orifice until a coating is formed, the size of the orifice and the speed of pouring being so correlated that liquid copper remains in said channel above the level of said orifice until thecoating 13 formed, and the temperature of said mold and of said molten metal being so correlated that the entering metal first solidifies nextthe inner wall while later solidifying metal a suitable mold casing and '5 filmed steelbillet within a suitable mold casing carrying an exterior channel communicating with the interior of said casing through a restricted orifice and casting molten copper into said channel in such manner that fluid copper remains in said channel above said orifice until sufiicient copper has entered the casing to fill up the space between the billet and the casing.

8. The process of making copper-clad steel which comprises film-coating a steel billet with copper, maintaining; the filmed billet within a casing containing an indiiferent atmosphere and castingmolten copper into a channel communicating with'the interior of said casing through a restricted ori-' fice, the level of the molten'copper in said channel being maintained abovesaid orifice until entering copper has filled the space between said billet and the mold casing.

In testimony whereof, I atfix my signature in the presence of witnesses.

WILLIAM MARSHALL PAGE, Witnesses:

P. M. WEIs, JOHN B. PATTON. 

